/*
 * Copyright © 2010-2012 Stéphane Raimbault <stephane.raimbault@gmail.com>
 *
 * SPDX-License-Identifier: LGPL-2.1-or-later
 */

#ifndef MODBUS_PRIVATE_H
#define MODBUS_PRIVATE_H

#ifndef _MSC_VER
# include <stdint.h>
# include <sys/time.h>
#else
# include "stdint.h"
# include <time.h>
typedef int ssize_t;
#endif
#include <sys/types.h>
#include "config.h"

#include "modbus.h"

MODBUS_BEGIN_DECLS

/* It's not really the minimal length (the real one is report slave ID
 * in RTU (4 bytes)) but it's a convenient size to use in RTU or TCP
 * communications to read many values or write a single one.
 * Maximum between :
 * - HEADER_LENGTH_TCP (7) + function (1) + address (2) + number (2)
 * - HEADER_LENGTH_RTU (1) + function (1) + address (2) + number (2) + CRC (2)
 */
#define _MIN_REQ_LENGTH 12

#define _REPORT_SLAVE_ID 180

#define _MODBUS_EXCEPTION_RSP_LENGTH 5

/* Timeouts in microsecond (0.5 s) */
#define _RESPONSE_TIMEOUT    500000
#define _BYTE_TIMEOUT        500000

typedef enum
{
	_MODBUS_BACKEND_TYPE_RTU = 0, _MODBUS_BACKEND_TYPE_TCP
} modbus_backend_type_t;

/*
 *  ---------- Request     Indication ----------
 *  | Client | ---------------------->| Server |
 *  ---------- Confirmation  Response ----------
 */
typedef enum
{
	/* Request message on the server side */
	MSG_INDICATION,
	/* Request message on the client side */
	MSG_CONFIRMATION
} msg_type_t;

/* This structure reduces the number of params in functions and so
 * optimizes the speed of execution (~ 37%). */
typedef struct _sft
{
	int slave;
	int function;
	int t_id;
} sft_t;

typedef struct _modbus_backend
{
	unsigned int backend_type;
	unsigned int header_length;
	unsigned int checksum_length;
	unsigned int max_adu_length;
	int (*set_slave)(modbus_t *ctx, int slave);
	int (*build_request_basis)(modbus_t *ctx, int function, int addr, int nb, uint8_t *req);
	int (*build_response_basis)(sft_t *sft, uint8_t *rsp);
	int (*prepare_response_tid)(const uint8_t *req, int *req_length);
	int (*send_msg_pre)(uint8_t *req, int req_length);
	ssize_t (*send)(modbus_t *ctx, const uint8_t *req, int req_length);
	int (*receive)(modbus_t *ctx, uint8_t *req);
	ssize_t (*recv)(modbus_t *ctx, uint8_t *rsp, int rsp_length);
	int (*check_integrity)(modbus_t *ctx, uint8_t *msg, const int msg_length);
	int (*pre_check_confirmation)(modbus_t *ctx, const uint8_t *req, const uint8_t *rsp, int rsp_length);
	int (*connect)(modbus_t *ctx);
	void (*close)(modbus_t *ctx);
	int (*flush)(modbus_t *ctx);
	int (*select)(modbus_t *ctx, fd_set *rset, struct timeval *tv, int msg_length);
	void (*free)(modbus_t *ctx);
} modbus_backend_t;

struct _modbus
{
	/* Slave address */
	int slave;
	/* Socket or file descriptor */
	int s;
	int debug;
	int error_recovery;
	struct timeval response_timeout;
	struct timeval byte_timeout;
	struct timeval indication_timeout;
	const modbus_backend_t *backend;
	void *backend_data;
	void (*recv_callback)(const void* buf, uint32_t len);  /* add:lakun@qq.com */
	void (*send_callback)(const void* buf, uint32_t len);  /* add:lakun@qq.com */
};

void _modbus_init_common(modbus_t *ctx);
void _error_print(modbus_t *ctx, const char *context);
int _modbus_receive_msg(modbus_t *ctx, uint8_t *msg, msg_type_t msg_type);

#ifndef HAVE_STRLCPY
size_t strlcpy(char *dest, const char *src, size_t dest_size);
#endif

MODBUS_END_DECLS

#endif  /* MODBUS_PRIVATE_H */
